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Biomedical subjects

S Raz

Publications and source records attributed to S Raz.

At least 109 records · Page 6Linked to original sources
PubMed1987

Physiological changes induced in cardiac myocytes by cytotoxic T lymphocytes.

The "lethal hit" induced by viral specific, sensitized, cytotoxic T lymphocytes (CTL) attacking virus-infected heart cells is important in the pathogenesis of viral myocarditis and reflects the key role of CTL in this immune response. The mechanisms involved are incompletely understood. Studies of the physiological changes induced in mengovirus-infected, cultured, neonatal, rat heart cells by CTL that had been previously sensitized by the same virus are presented. The CTL were obtained from spleens of mengovirus-infected, major histocompatibility complex (MHC) matched adult rats. Cell wall motion was measured by an optical method, action potentials with intracellular microelectrodes, and total exchangeable calcium content by 45Ca tracer measurements after loading the myocytes with 45Ca and then exposing them to CTL. After 50 min (mean time) of exposing mengovirus-infected myocytes to the CTL, the mechanical relaxation of the myocyte was slowed, with a subsequent slowing of beating rate and a reduced amplitude of contraction. Impaired relaxation progressed, and prolonged oscillatory contractions lasting up to several seconds appeared, with accompanying oscillations in the prolonged plateau phase of the action potentials. Arrest of the myocyte contractions appeared 98 min (mean time) after exposure to CTL. These changes in action potentials and contractions were reversible either by washout with the normal medium or by the addition of verapamil. The amount of total exchangeable calcium in the cultured myocytes, 1 h after exposure to CTL, was significantly increased. This increase was prevented by pretreatment with verapamil. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Relationship between cognitive and morphological asymmetry in dementia of the Alzheimer type: a CT scan study.

In this study we investigated the association between morphological asymmetry and patterns of cognitive ability in dementia of Alzheimer's type (DAT). Digitized CT scans were used to estimate volumetric parameters of the brain. The volume of the cranium, brain parenchyma, the subarachnoid space, and lateral ventricles was computed. The volume of the subarachnoid space was used as an index of cortical atrophy, while the ventricular volume served as an estimate of subcortical atrophy. Asymmetry indices were computed for all structures as the difference between left and right volume divided by their average and multiplied by 100. Cognitive asymmetry index was computed by dividing the difference between VIQ and PIQ of the Wechsler Adult Intelligence Scale (WAIS) by their average and multiplying by 100. After statistically controlling for cranial asymmetry, hemispheric asymmetry was found to correlate positively with cognitive asymmetry. The correlation was somewhat greater for male than for female patients. Asymmetry of both cortical and subcortical atrophy correlated negatively with cognitive asymmetry.

Aged↗
PubMed1987

Fat-free diet and myocardial excitability, refractoriness and ventricular fibrillation.

The lipid composition of the sarcolemma influences its function. The purpose of this study is to investigate the electrophysiological alterations induced in the rat's heart by dietary manipulation of cardiac fatty-acid composition. Strength-duration and strength-interval relationships were used to study excitability and refractoriness respectively. Ventricular fibrillation threshold measured by short bursts of rapid stimulation was used to indicate ventricular vulnerability. Gas liquid chromatography was used to analyse cardiac fatty-acid-composition. We used two-week-old rats fed with fat-free diet and 5% and 10% soya bean oil-supplemented diets for 6-9 weeks. Fat-free diet only was associated with increased eicosatrienoic acid content, a marker of essential fatty-acid deficiency. A decrease in poly-unsaturated to saturated (P:S) fatty-acid ratio was also observed. Five percent oil supplementation was associated with a delay and attenuation of this effect. Fat-free diet was associated with increased excitability, decreased refractoriness and reduced ventricular fibrillation threshold. Ten percent oil supplementation prevented these effects while 5% oil supplementation had only a temporary protective effect. We conclude that manipulation of dietary fat content can affect cardiac fatty-acid composition and electrophysiology.

Animals↗
PubMed1987

Dietary lipid intake and myocardial electrophysiology.

We studied the effect of a fat-free diet on the cardiac electrophysiology of rats. Fourteen 2-week-old rats were maintained on a fat-free diet and 12 rats had a 5% soybean oil supplement to their diet. The rats were killed after 6 weeks and the hearts mounted on a Langendorff chamber. Atrioventricular (A-V) block was induced. Myocardial strength-duration (S-D) and strength-interval (S-I) curves were determined. A significant depletion of linoleic acid and elevation of palmitoleic, stearic, and oleic acids was found in the hearts obtained from rats on fat-free diet as compared with the hearts obtained from the rats on oil-supplemented diets. Hearts obtained from rats who had had the oil supplement had a shorter refractory period and an increased threshold for excitation; therefore, these hearts should be less vulnerable to cardiac dysrhythmias. Both S-D and S-I curves best fitted a logarithmic relationship. The intercepts and slopes of these curves were significantly different in the two groups. There were significant correlations between myocardial fatty acid composition (stearate and linoleate in particular) and the different electrophysiological parameters.

Animals↗
PubMed1986

T-2 toxin effect on cultured myocardial cells.

Beat rate, contractility and viability of cultured myocardial cells perfused with solutions containing various concentrations of T-2 toxin were studied. While doses below 50 micrograms/ml had no immediate effect, those above 250 micrograms/ml decreased beat rate and amplitude. After 10-30 min of perfusion most cells stopped beating and did not restart after withdrawal of toxin. Nevertheless, most cells remained viable as judged by morphology and trypan blue exclusion. A 24-h exposure to doses of 5 or 2.5 micrograms/ml of toxin decreased the beat rate and inotropic responses of the myocytes. After 48 h cell death ensued. Thus T-2 toxin has some direct toxicity to myocardial cells but the lethal dose seems too high to make this the cause of cardiovascular failure.

Animals↗
PubMed1986

Fracture of semirigid penile prosthesis: a rare complication.

We report 3 cases of fractured semirigid Small-Carrion and Finney penile prostheses. All prostheses had been in place and functional for at least 2 years before fracture. We may begin to see more complications associated with material failure.

Adult↗
PubMed1986

Genitourinary dysfunction in a geriatric outpatient population.

Clinical and urodynamic findings in 167 women and 96 men, aged 65 years and older evaluated consecutively during a four-year period in an outpatient urodynamic laboratory, are presented and compared with findings from other studies of geriatric populations. Seventy-three percent of the patients (81% of the women and 60% of the men) presented with symptoms of incontinence, most commonly of the mixed type. Although pathological lesions such as tumors and stones were rare, urodynamic abnormalities were common. Urodynamic evidence of sphincter weakness in women and detrusor motor instability were the most common urodynamic findings among patients who presented with incontinence. Close to 20% of patients who presented without incontinence also had one or more of these findings. Approximately one-third of patients had multiple urodynamic findings, emphasizing the complexity of the pathophysiology, diagnosis, and treatment of genitourinary dysfunction in many geriatric patients. Despite the long duration of symptoms in most patients, the majority were substantially improved after diagnosis and treatment of the specific genitourinary and urodynamic abnormalities detected.

Aged↗
PubMed1986

Surgical treatment for female geriatric incontinence.

Surgery may be the most effective treatment for incontinence in the elderly female patient. Today, most of these incontinent patients are cured with surgery using the transvaginal approach, an access at low risk (especially for the geriatric female population). Surgery for stress urinary incontinence of all grades is established; however, surgical treatment for urge incontinence due to bladder instability is still controversial.

Aged↗
PubMed1986

[Urethral replacement in women. Experimental works and clinical application].

Numerous operations have been previously described in view of replacing the urethra, but attempts to provide continence have rarely been satisfactorily achieved. Urethral replacement using ileum with an ileal intussuspected valve for continence has be39 successfully performed in ten dogs. This report details the experimental model with the results obtained in the long range. It is followed by the evaluation, surgical technique and postoperative results of the clinical application of this surgical alternative in three patients.

Adult↗